A gas turbine engine of the turbofan type generally includes, from forward to aft a forward fan, a low pressure compressor, a higher pressure compressor, a burner, a high pressure turbine, and an aft low pressure power turbine. The higher pressure compressor and high pressure turbine of the core engine are connected by a first shaft. The low pressure turbine and the fan are connected by a second shaft that rotates with the first shaft that connects the high pressure turbine and the higher pressure compressor. Air passes through the fan, is compressed by the low pressure turbine, is compressed further by the higher pressure turbine, and is mixed with fuel and ignited in the burner. After ignition, the highly energized gas stream expands thereby, in sequence rotating the high pressure turbine to rotate the higher pressure compressor, rotating the low pressure turbine to rotate the fan, and exhausting from the engine.
In a turbofan engine, some thrust is produced by the highly energized gas stream exiting the engine, most of the thrust produced is generated by the forward fan. In a turbojet engine, in contrast, much of an engine thrust is produced by the exiting of the highly energized gas stream.
An engine frame may be used to support the bearings of the engine's turbines. Bearing support frames, however, may be heavy. The frames may also be subject to thermal stresses, thermal gradients and may require heat shields if subjected to hot flow path gases. Other prior art supports use an inner ring structure mounting to an inner annular bearing. The ring structure attaches to a plurality of tie rods that attach to the inner annular ring, an intermediate support structure and an engine casing.